Aziridines with a strained ring are of paramount importance in organic synthesis since they are valuable precursors of amino sugars, alkaloids, substituted α-amino acids or present in natural products such as mitomycins [Padwa, A.; Woolhouse, A. D. In Comprehensive Heterocyclic Chemistry; Lwowski, W.; Ed.; Pergamon: Oxford, 1984; Vol. 7, pp 47] and azinomycins [Hodgkinson, T. J.; Shipman, M. Tetrahedron, 2001, 57, 4467] that exhibit potent biological activity.
Aziridination of olefins are among the most useful transformations in organic synthesis [J. B. Sweeney, Chem. Soc. Rev. 2002, 31, 247; W. McCoull, F. A. Davies, Synthesis 2000, 1347] since aziridines constitute a key structural feature of several classes of natural products and are extremely versatile building blocks that can undergo synthetically useful transformations [W. McCoull, F. A. Davies, Synthesis 2000, 1347; A. Cardillo, L. Gentilucci, A. Tolomelli, Aldrichimica Acta 2003, 36, 39].
Aziridines can be found in natural products such as mitomycin, porfiromycin, and mitiromycin, which are potent antitumor and antibiotic agents [D. Tanner, Angew. Chem. Int. Ed. Engl. 1994, 33,599] Also, many biologically active compounds such as amino acids, β-lactam antibiotics and alkaloids have been derived from aziridines.
Classical method for the preparation of aziridine has been disclosed by Wenker and Hoch-Campbell in 1934 [H. Wenker, J. Am. Chem. Soc. 1935, 57, 2328; J. Hoch, Compt. Rend. 1934, 198, 1865; and K. N. Campbell, B. K. Campbell, J. F. McKenna, E. P. Chaput, J. Org. Chem. 1943, 8, 103]
U.S. Pat. No. 5,929,252 discloses a process for direct aziridination of olefins as well as a wide range of allylic alcohols employing phenyl trimethyl ammonium tribromide (PTAB) as a catalyst and N-iodo-N-chloro sulfonamides, chloramine salts, as the nitrogen source.
Article titled “The asymmetric synthesis of aziridines” by Helen M. I. Osborn and Joseph Sweeney in Tetrahedron: Asymmetry, Volume 8, Issue 11, 12 Jun. 1997, Pages 1693-1715 doi:10.1016/S0957-4166(97)00177-8, discloses methods for asymmetric preparation of a range of 1H-aziridines and their N-substituted analogues in presence of chiral catalysts.
Article titled “Unexpected Multiple Electrophilic Addition Reaction of (Z)-Alk-2-en-4-yn-oates with N,N-Dibromo-p-toluene sulfonmide (TsNBr2): A Highly Diastereoselective Synthesis of Densely Functionalized Aziridines” by Shen, Huang, Xiang et al in ORGANIC LETTERS 11 (24): 5698-5701 DEC 17 2009; ISSN: 1523-7060; DOI: 10.1021%1902446h, discloses electrophilic addition reaction of (Z)-alk-2-en-4-ynoates and TsNBr2 to obtain aziridine derivatives.
Article titled “Pyridiniumhydrobromideperbromide: a versatile catalyst for aziridination of olefins using Chloramine-T” by Ali S I, Nikalje M D, Sudalai Org Lett. 1999 Sep. 9; 1(5): 705-7 discloses Pyridiniumhydrobromideperbromide (Py×HBr3) as a catalyst for the aziridination of electron-deficient as well as electron-rich olefins using Chloramine-T as a nitrogen source to obtain the corresponding aziridines.
Article titled “Iodine-catalyzed aziridination of alkenes using Chloramine-T as a nitrogen source” by Takeya Ando, in Tetrahedron Volume 54, Issue 44, 29 Oct. 1998, Pages 13485-13494 having doi: 10.1016/S0040-4020(98)00827-8 discloses aziridination of alkenes utilizing Chloramine-T (N-chloro-N-sodio-p-toluenesulfonamide) as a nitrogen source and in presence of a catalyst.
Several reported methods for aziridination reactions are known that employ catalysts such as Cu [Knight, J. G.; Muldowney, M. D. Synlett 1995, 949]; Co [Gao, G.-Y.; Harden, J. D.; Zhang, X. P. Org. Lett. 2005, 7, 3191]; Rh [Breslow, R.; Gellman, S. H. J. Am. Chem. Soc. 1983, 105, 6728]; Ag [Cui, Y.; He, C. J. Am. Chem. Soc. 2003, 125, 16202]; Pd [Majumdar, K. C.; Mondal, S.; De, N. Synlett, 2008, 2851], etc., which generates in situ metal-nitrene species (PhI═NTs) in presence of sulfonamide and oxidant.
However, the reagents employed in the prior art methods are complex, require large excess of olefins, are costly or involve toxic heavy metals. Also the earlier methods for the preparation of aziridine shows that the reactions are drastic on using metal catalysts, separation of metals from the final aziridines products was tedious. Hence, it is desirable to provide an inexpensive, easy and environmentally benign method of aziridination.